Amiga 500 Panasonic floppy issue - spindle plate not meeting disk

sirlemonhead · 09 March 2016, 17:04

Hi,

A few years ago I got a free A500 with a few issues, one of which was a broken floppy drive. I don't remember what was wrong with it then but I did a few things like disassemble it to try get it working (so it's definitely become unaligned since)

It's got a Panasonic JU-253-033P floppy drive. It's been sat in a box for the last few years as I also got a free A1200 not long after so the A500 was kinda forgotten about.

I've been trying to resurrect the A500 and the floppy drive recently. The capacitor at the front near the spindle plate looked like it had leaked so I've replaced that. I also gave it a good clean and sprayed some contact cleaner on the disk detection pins.

It all seems to function correctly now except for one issue that looks mechanical. I have the top cover off the drive and If I put in a disk, I can hear the spindle plate spinning (and see it from the front) but the actual disk itself isn't spinning.

Comparing with another working floppy drive, I can see that when a disk is inserted, there's a few mm's gap between the disk and the spindle plate. It looks like it's not making contact with the disk so is unable to spin it.

I can't physically push or shift anything on the drive to close this gap, so I don't think it's anything to do with weak springs.

Is it possible that the spindle plate has somehow lowered a few millimetres? Does anyone know how I can actually remove the spindle plate? it seems really well stuck on and I'm afraid if I try pry it, it'll break. The drive was quite dirty so I'd like to at least look under it to see if it's got some crud under it.

Here's some pictures of the spindle plate. Does anyone see anything unusual, specifically with that little...round metal bit that you can push up and down? It's not the very centre spindle shaft but the little nub near the centre.

https://dl.dropboxusercontent.com/u/...00floppy_1.jpg
https://dl.dropboxusercontent.com/u/...00floppy_2.jpg
https://dl.dropboxusercontent.com/u/...00floppy_3.jpg
https://dl.dropboxusercontent.com/u/...00floppy_4.jpg

Thanks!

Daedalus · 09 March 2016, 17:43

Normally the floppy drive mechanically moves the disk down onto the spindle when it's inserted, and lifts it up to eject it. That whole mechanism is missing in your photos - if it's there, it's probably damaged or loose. If it's not there, well then there's your problem

The spindle won't move because it looks like it's correctly aligned with its sensors on the main PCB. The coils are probably also soldered onto that PCB, so if it spins it's probably in the correct position.

The spring loaded nub off-centre from the main spindle looks normal to me. It gets pressed in when the disk is inserted and does one revolution to catch the nub in the slot in the disk's hub.

Oh, and welcome along!

sirlemonhead · 09 March 2016, 18:37

Thanks!

Yeah I have most of the assembly removed so I could get photos of the spindle plate.

What do you mean when you say "The spindle won't move because it looks like it's correctly aligned with its sensors on the main PCB" ?

I know there's a little sensor (magnetic?) at the front of the plate, but the spindle does move without issue. Do you mean it's not removable because of this?

The coils being soldered to the PCB is normal right? Then the plate itself sits on top and the magnetic magic field makes it rotate. It's not possible for the plate to sit lower than it should? I can't see much wrong with the assembly at all unfortunately.

Daedalus · 09 March 2016, 19:25

I mean it won't move vertically, as in up to meet the floppy disk. It looks in the right place to me and if it spins freely then I doubt there's anything wrong with that end of things. The problem must be to do with the upper mechanism - it should snap down when the disk is fully inserted. Perhaps there's a part of that that has been slightly bent, causing it not to move down as it should.

sirlemonhead · 09 March 2016, 21:45

Is it the little nub that actually spins the disk? In comparison to a working drive, it seems a lot lower than a working drive I have (Panasonic JU-256A216P)

I took the the whole bottom and top disk cage/mount assembly from this drive and put it in the Amiga one, and the disk still did not spin.

Here's the good drive:
https://dl.dropboxusercontent.com/u/.../gooddrive.jpg

And the bad A500 drive:
https://dl.dropboxusercontent.com/u/...0/baddrive.jpg

I can't see the bad drive catching the disk properly

Daedalus · 09 March 2016, 22:14

Hmmm... You may have a point when you see it from that angle. The hub of the floppy should sit flush with the spinning disc of the drive, so that little nub only needs to protrude by about 1mm to catch the disk.

sirlemonhead · 09 March 2016, 22:16

Is there a way I can pop the plate off? I see lots of "floppy drive teardown" articles on google but they seem to suggest it can just be lifted off, which doesn't seem the case with the Panasonic drives...

Daedalus · 10 March 2016, 00:26

I don't know the drive well enough to say. The Chinon drives have a couple of screws holding a flywheel onto the spindle on the other side of the PCB if I remember correctly, but that looks to be a different design so I've no idea I'm afraid.

sirlemonhead · 10 March 2016, 19:27

No worries, thanks for the help

It's always good to have another set of eyes look at these things.

Maybe I'll just be a bit more forceful with it... not a lot to lose at this stage!

idrougge · 08 March 2018, 21:43

I thought I'd just highjack this thread…

I have a Panasonic JU-253 where there was notable capacitor leakage in the front of the drive. I managed to replace the 10 µF capacitor using hot air after some major cleaning and flux application. But the drive makes a disturbing sound when spinning and fails to recognise disks as bootable.

Beyond repair, I thought, until I pressed on the spindle nub on the bottom, which made the drive go quiet and actually read disks without error. So it seems as though the nub has gone loose. Unfortunately, the nub is of the kind without any slits, so how do I tighten it?

sirlemonhead · 09 March 2018, 00:56

I ended up popping the spindle plate off in the end, in an attempt to fix the nub.

I can't really remember what I did exactly, but I managed to get the nub to raise up a bit, back to the normal location. The drive still didn't work after as I think I probably ruined the stepper motor alignment and god knows what else from all the tinkering I did.

To pop the spindle plate off:

If you look at the underside of the drive, the centre of the spindle is silver and sits within an outer gold coloured ring. I used something flat, about the diameter of the gold part, to push down on the silver part. This made a "pop" noise and the silver part lowered ever so slightly, flush with the gold outer ring.

then I used something the diameter of the silver part to push on the silver part, popping it out completely. and separating the spindle plate from the drive.

Not sure why I had to do it that way but it was the only thing that worked! hope that makes sense.

Not too sure what you mean about the slit in the nub but if you can take a picture of what you mean I can try help?

09 March 2016, 17:04	#1
sirlemonhead Registered User Join Date: Mar 2016 Location: Dublin Posts: 31	Amiga 500 Panasonic floppy issue - spindle plate not meeting disk Hi, A few years ago I got a free A500 with a few issues, one of which was a broken floppy drive. I don't remember what was wrong with it then but I did a few things like disassemble it to try get it working (so it's definitely become unaligned since) It's got a Panasonic JU-253-033P floppy drive. It's been sat in a box for the last few years as I also got a free A1200 not long after so the A500 was kinda forgotten about. I've been trying to resurrect the A500 and the floppy drive recently. The capacitor at the front near the spindle plate looked like it had leaked so I've replaced that. I also gave it a good clean and sprayed some contact cleaner on the disk detection pins. It all seems to function correctly now except for one issue that looks mechanical. I have the top cover off the drive and If I put in a disk, I can hear the spindle plate spinning (and see it from the front) but the actual disk itself isn't spinning. Comparing with another working floppy drive, I can see that when a disk is inserted, there's a few mm's gap between the disk and the spindle plate. It looks like it's not making contact with the disk so is unable to spin it. I can't physically push or shift anything on the drive to close this gap, so I don't think it's anything to do with weak springs. Is it possible that the spindle plate has somehow lowered a few millimetres? Does anyone know how I can actually remove the spindle plate? it seems really well stuck on and I'm afraid if I try pry it, it'll break. The drive was quite dirty so I'd like to at least look under it to see if it's got some crud under it. Here's some pictures of the spindle plate. Does anyone see anything unusual, specifically with that little...round metal bit that you can push up and down? It's not the very centre spindle shaft but the little nub near the centre. https://dl.dropboxusercontent.com/u/...00floppy_1.jpg https://dl.dropboxusercontent.com/u/...00floppy_2.jpg https://dl.dropboxusercontent.com/u/...00floppy_3.jpg https://dl.dropboxusercontent.com/u/...00floppy_4.jpg Thanks!

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09 March 2016, 17:43	#2
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,351	Normally the floppy drive mechanically moves the disk down onto the spindle when it's inserted, and lifts it up to eject it. That whole mechanism is missing in your photos - if it's there, it's probably damaged or loose. If it's not there, well then there's your problem The spindle won't move because it looks like it's correctly aligned with its sensors on the main PCB. The coils are probably also soldered onto that PCB, so if it spins it's probably in the correct position. The spring loaded nub off-centre from the main spindle looks normal to me. It gets pressed in when the disk is inserted and does one revolution to catch the nub in the slot in the disk's hub. Oh, and welcome along!

09 March 2016, 18:37	#3
sirlemonhead Registered User Join Date: Mar 2016 Location: Dublin Posts: 31	Thanks! Yeah I have most of the assembly removed so I could get photos of the spindle plate. What do you mean when you say "The spindle won't move because it looks like it's correctly aligned with its sensors on the main PCB" ? I know there's a little sensor (magnetic?) at the front of the plate, but the spindle does move without issue. Do you mean it's not removable because of this? The coils being soldered to the PCB is normal right? Then the plate itself sits on top and the magnetic magic field makes it rotate. It's not possible for the plate to sit lower than it should? I can't see much wrong with the assembly at all unfortunately.

09 March 2016, 19:25	#4
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,351	I mean it won't move vertically, as in up to meet the floppy disk. It looks in the right place to me and if it spins freely then I doubt there's anything wrong with that end of things. The problem must be to do with the upper mechanism - it should snap down when the disk is fully inserted. Perhaps there's a part of that that has been slightly bent, causing it not to move down as it should.

09 March 2016, 21:45	#5
sirlemonhead Registered User Join Date: Mar 2016 Location: Dublin Posts: 31	Is it the little nub that actually spins the disk? In comparison to a working drive, it seems a lot lower than a working drive I have (Panasonic JU-256A216P) I took the the whole bottom and top disk cage/mount assembly from this drive and put it in the Amiga one, and the disk still did not spin. Here's the good drive: https://dl.dropboxusercontent.com/u/.../gooddrive.jpg And the bad A500 drive: https://dl.dropboxusercontent.com/u/...0/baddrive.jpg I can't see the bad drive catching the disk properly

09 March 2016, 22:14	#6
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,351	Hmmm... You may have a point when you see it from that angle. The hub of the floppy should sit flush with the spinning disc of the drive, so that little nub only needs to protrude by about 1mm to catch the disk.

09 March 2016, 22:16	#7
sirlemonhead Registered User Join Date: Mar 2016 Location: Dublin Posts: 31	Is there a way I can pop the plate off? I see lots of "floppy drive teardown" articles on google but they seem to suggest it can just be lifted off, which doesn't seem the case with the Panasonic drives...

10 March 2016, 00:26	#8
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,351	I don't know the drive well enough to say. The Chinon drives have a couple of screws holding a flywheel onto the spindle on the other side of the PCB if I remember correctly, but that looks to be a different design so I've no idea I'm afraid.

10 March 2016, 19:27	#9
sirlemonhead Registered User Join Date: Mar 2016 Location: Dublin Posts: 31	No worries, thanks for the help It's always good to have another set of eyes look at these things. Maybe I'll just be a bit more forceful with it... not a lot to lose at this stage!

08 March 2018, 21:43	#10
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,338	I thought I'd just highjack this thread… I have a Panasonic JU-253 where there was notable capacitor leakage in the front of the drive. I managed to replace the 10 µF capacitor using hot air after some major cleaning and flux application. But the drive makes a disturbing sound when spinning and fails to recognise disks as bootable. Beyond repair, I thought, until I pressed on the spindle nub on the bottom, which made the drive go quiet and actually read disks without error. So it seems as though the nub has gone loose. Unfortunately, the nub is of the kind without any slits, so how do I tighten it?

09 March 2018, 00:56	#11
sirlemonhead Registered User Join Date: Mar 2016 Location: Dublin Posts: 31	I ended up popping the spindle plate off in the end, in an attempt to fix the nub. I can't really remember what I did exactly, but I managed to get the nub to raise up a bit, back to the normal location. The drive still didn't work after as I think I probably ruined the stepper motor alignment and god knows what else from all the tinkering I did. To pop the spindle plate off: If you look at the underside of the drive, the centre of the spindle is silver and sits within an outer gold coloured ring. I used something flat, about the diameter of the gold part, to push down on the silver part. This made a "pop" noise and the silver part lowered ever so slightly, flush with the gold outer ring. then I used something the diameter of the silver part to push on the silver part, popping it out completely. and separating the spindle plate from the drive. Not sure why I had to do it that way but it was the only thing that worked! hope that makes sense. Not too sure what you mean about the slit in the nub but if you can take a picture of what you mean I can try help?

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